Development of Pre-Harvest Monitoring Sentinel for Strategic Decision-Making in Beef Processing

Food safety is a prominent concern for food products in the United States. The Centers for Disease Control and Prevention (CDC) estimates that each year 48 million people get sick, 128,000 are hospitalized, and 3,000 die from foodborne diseases in the Unites States [39]. Foodborne illnesses can be caused by many known bacteria, viruses, and toxins that are transmitted into foods through many different routes, one commonly being foodborne diseases that originate from livestock. Naturally, livestock, like cattle, harbor a wide variety of microorganisms, some of which have been identified as foodborne pathogens and have the potential to enter the food supply chain and impact public health. Cattle have been identified as reservoirs for foodborne pathogens such as Escherichia coli O157:H7, Salmonella, and Shiga toxin-producing E. coli (STEC). These pathogens are colonized in the gastrointestinal (GI) tract of the animal, and while these pathogens are harmless to the animal, they are known to cause severe illness in humans. They are shed in the feces of the animal, which then leads to contamination of the hides and ultimately leads to carcass contamination and can remain in the final meat product. Ground beef is a commonly known vehicle for these pathogens mentioned above. According to the Interagency Food Safety Analytics Collaboration (IFSAC), in 2019 beef contributed to 24.3% of foodborne E. coli O157:H7 illnesses and 6.2% of Salmonella illnesses [18]. Much effort has been put in by the processors to control these pathogens in beef products post-harvest and have made tremendous advancements that have led to a reduction in attribution from beef; however, these issues also warrant management strategies geared towards controlling the incoming pathogen loads entering the commercial abattoirs on harvest-ready feedlot cattle. Research has proven that cattle hides are a large source of carcass contamination, and a large source of hide contamination occurs during transportation from the feedlots to the processing facilities and the time spent in the lairage of the processing facilities. The Food Safety and Inspection Service (FSIS) has no statutory authority on the cattle farms/feedlots; therefore, the implementation of pre-harvest interventions cannot be required for cattle producers. The FSIS can however regulate the lairage area of beef processing facilities; therefore, pre-harvest monitoring strategies in the lairage area need to be developed and adopted by the industry. Having a better understanding of pathogens present in the lairage area and incoming pathogen loads on the cattle will allow for more strategic decision making by beef processors and can overall help make the food supply chain safer. The first chapter of this thesis focuses on the development and validation of pre-harvest sampling strategies to monitor pathogens in the lairage area of commercial beef processing facilities. The objective of this study was to establish pre-harvest monitoring sentinel by evaluating three different sampling methods in the lairage area to determine incoming pathogen prevalence from the cattle to inform in-plant decision making. Sampling methods for this study included fecal pats, boot swabs, and MicroTally swabs to collect fecal material from the pen floor environment of the cattle holding pens in the lairage area and were analyzed for the prevalence of E. coli O157:H7, Salmonella, and six STECs. The results indicate that boot swabs were the best sampling method in the lairage area to detect for the presence of pathogens as they were effective, the least labor intensive, and inexpensive. The second chapter validates Finalyse™ as a bacteriophage hide application to reduce pathogens in a commercial beef processing facility. Finalyse™ uses naturally occurring phages to weaken the E. coli O157:H7 cell wall and replicate, destroying additional bacteria on the cattle hides, The objective of this study was to evaluate the efficacy of Finalyse™, as a pre-harvest intervention, on the reduction of pathogens, specifically E. coli O157:H7, on the cattle hides and pen floor environment of the lairage area to overall reduce incoming pathogen loads. Hide swabs were taken to evaluate the efficacy of Finalyse™ on the cattle hides and boot swabs were taken to monitor the pen floor environment in the lairage area. The results indicate that Finalyse™ was effective on reducing E. coli O157:H7 prevalence in the pen floor environment where the intervention was being applied. Finally, the third chapter evaluated the changes in pathogen prevalence and indicator bacteria in cattle lairage areas of a commercial beef processing facility over a year period. The objective of this study was to monitor the changes in pathogen prevalence and indicator bacteria in the lairage area to assist in important plant making decisions. This was conducted through the enumeration of indicator bacteria, detection of pathogens (STECs and Salmonella), and quantification of Salmonella from boot swab samples that collected fecal material from the cattle holding pens throughout the lairage area. Data collected was provided to plant personnel and overall strengthened in-plant decision making.